JPH1091990A - Objective lens tilt driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the inclination of a beam optical axis to a disk recording surface with low power consumption, by high performance and at a high speed by composing two pairs of supporting members orthogonal to each other of pairs of elastic materials disposed linear-symmetrically to an optical axis sandwiching an objective lens. SOLUTION: An objective lens 2 for converging luminous fluxes made incident on an optical disk is supported by an annular objective lens holder 9, and an annular relaying member 7 and a fixing member B are disposed to be concentric-circular outside of the objective lens holder 9. The objective lens holder 9 and the annular relaying member 7 are connected and supported by a pair of supporting members 5a and 5b. The relaying member 7 and the fixing member 8 are connected and supported by a pair of supporting members 6a and 6b. The supporting members 5a and 5b and the supporting members 6a and 6b are disposed orthogonal to each other so as to support the objective lens 2 so as to be rotated in two inclining directions orthogonal to the optical axis 4 of the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording and / or reproducing information signals on an optical recording medium such as an optical disk. The present invention relates to an objective lens tilt drive device that can be controlled at a high speed so as to be perpendicular to an information recording surface.

[0002]

2. Description of the Related Art In an optical disk device, that is, a device for irradiating a signal recording surface of a rotationally driven optical disk with a light beam to read an information signal recorded on the optical disk or to write an information signal on the optical disk, the information signal is written. An optical head is used as means for (recording) / reading (reproduction). This optical head is
A light source such as a semiconductor laser element, an optical element such as a collimator lens or a beam splitter, and an objective lens and a photodetector are configured as main elements. Through an objective lens, focused on the recording surface of the optical disk by the objective lens, and detects a light beam reflected by the recording surface with a photodetector to record or reproduce an information signal. .

[0003] The objective lens is driven by an objective lens driving device by electromagnetic driving force in two directions: an optical axis direction (focusing direction) and a direction orthogonal to the optical axis direction (tracking direction).
It is driven for displacement in the axial direction. As a result, the light beam is focused on the recording surface of the optical disk and scans the recording track accurately. In general, the movable range of the objective lens by the objective lens driving device that drives only the objective lens is the focusing direction of both the optical head integrated with the optical system and the optical head separated from the optical system in which only the optical system is separated and fixed. Is ±
0.6 mm and the tracking direction is about ± 0.4 mm.

In general, an optical recording disk is a molded part made of a resin such as polycarbonate or acrylic, and thus is liable to be statically warped or deformed after molding. When there is such a static warp, the disk pit surface is tilted due to the warp, and the return light with respect to the incident light has an angle, and the optical axis is shifted. This deviates from the viewing angle, and the return light output is reduced. In addition, when the pit surface is tilted, the track pitch between the adjacent tracks becomes narrower equivalently. If the beam spot diameter on the pit surface is fixed, the influence of the pit information of the adjacent track is reduced. Susceptible to this, leading to an increase in crosstalk.

[0005] In order to improve the performance deterioration as described above, the optical system body including the objective lens is moved along with the static warpage so that the optical axis is always perpendicular to the pit surface. There is known a reproducing apparatus having a tilt servo mechanism that can be rotated in a plane including the following. However, the reproducing apparatus having such a tilt servo mechanism has a problem that it can follow only a static warpage.

Japanese Patent Application Laid-Open No. 7-65397 (hereinafter referred to as a known example) eliminates signal quality deterioration due to the inclination between the disk recording surface and the beam optical axis, and suppresses changes in the amount of warpage during one round of the disk. An optical disk device capable of correcting the inclination of the beam optical axis at high speed is disclosed. In this known example, an objective lens holder that holds an objective lens is supported by a plurality of elastic bodies so as to be rotatable in a focusing direction, a tracking direction, and a tilt direction of an optical axis of the objective lens. A plurality of coils for focusing, tracking, and tilt are attached to the objective lens holder.

However, in the configuration shown in this known example,
Since the objective lens holder is movable in the focusing direction, the tracking direction, and the tilt direction of the optical axis of the objective lens, the objective lens holder that is a movable body becomes large, and the objective lens is tilted in the tilt direction of the optical axis. In the case where the objective lens moves, the objective lens is shifted from the optical axis of the incident light beam in proportion to the distance from the rotation center of the objective lens holder to the objective lens. Further, in order to rotate a large and heavy objective lens holder equipped with a large number of focusing coils and tracking coils in a tilt direction of the optical axis of the objective lens at a predetermined angular acceleration,
A large driving force is required, resulting in an increase in power consumption.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of the change in the amount of warpage during one round of the disk. Low power consumption and high performance
It is an object of the present invention to provide an objective lens tilt drive device capable of correcting at high speed.

[0009]

In order to solve the above-mentioned problems, the present invention (claim 1) provides an objective lens for condensing light on an optical disk, and moving the objective lens in a first tilt direction of an optical axis thereof. A pair of first support members rotatably supported, a relay member fixed to a part of the pair of first support members, a part of which is attached to the relay member, and the objective lens; A pair of second support members rotatably supported in a second tilt direction orthogonal to the first tilt direction, a fixed member to which a part of the pair of second support members is fixed, and the object The lens is moved to the first support member by using the first support member as a rotation axis.
And a driving means for rotating in a second inclination direction with the second support member as a rotation axis in the inclination direction of the first lens and the second lens. Wherein each of the support members comprises a pair of elastic members disposed symmetrically with respect to the optical axis with the objective lens interposed therebetween.

According to the present invention (claim 2), in the above-mentioned objective lens tilt drive device (claim 1), the first and second tilt directions correspond to a disc radial direction and a disc tangential direction, respectively. It is characterized by.

The present invention (Claim 3) is characterized in that, in the above-mentioned objective lens tilt drive device (Claim 2), the center axis of rotation of the second support member coincides with the disk radial direction.

According to a fourth aspect of the present invention, in the above-described objective lens tilt driving device (the first to third aspects), the rotation center axes of the first and second support members are respectively set to the first and second support members. The two supporting members each include a center of gravity of a rotating part that supports the rotation.

According to the present invention (claim 5), in the above-mentioned objective lens tilt driving device (claim 4), the respective rotation center axes of the first and second support members are the same which are orthogonal to the optical axis. It is characterized by being arranged on a plane.

According to a sixth aspect of the present invention, in the above-mentioned objective lens tilt drive device, the same plane orthogonal to the optical axis is a main plane of the objective lens.

In the objective lens tilt drive device configured as described above, the following specific modes are possible. 1. The first and second support members are wire-like elastic bodies.

2. The cross-sectional shape of the wire-shaped elastic body is substantially circular. 3. The first and second support members are elastic bodies made of a resin material. In the objective lens tilt drive device of the present invention configured as described above, the respective rotation center axes of the two pairs of support members (first and second support members) supporting the objective lens are orthogonal to the optical axis. Since the same plane that is disposed on the same plane and that is orthogonal to the optical axis coincides with the main plane of the objective lens, the objective lens is disposed to rotate the objective lens in the tilt direction of the optical axis. Even if the objective lens is rotated in two orthogonal tilt directions of the optical axis of the objective lens by the driving means, the rotation center of the objective lens is located at the principal point of the objective lens.
The beam spot on the disk does not move in the disk radial direction (disk radial direction) and the disk tangential direction (disk tangential direction), so that stable actuator control can be realized.

In addition, since the extremely small and lightweight rotating portion, which is composed of the objective lens and a part of the driving means, is rotated at a predetermined angular acceleration in the tilt direction of the optical axis of the objective lens, the driving force is small. As a result, the power consumption is small. In this way, the inclination of the beam optical axis with respect to the disk recording surface can be corrected with low power consumption, high performance, and high speed in response to the change in the amount of warpage during one round of the disk.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a configuration of an objective lens tilt driving device 1 according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. It is sectional drawing seen from the -B line. The objective lens tilt drive device 1 is a device that tilts and drives the objective lens 2 at high speed in two rotation directions, a disk radial rotation direction (disk radial direction) and a disk tangential rotation direction (disk circumferential direction).

In the objective lens tilt driving device 1 shown in FIG. 1, the objective lens 2 for condensing the incident light beam 3 on an optical disk (not shown) is supported by an annular objective lens holder 9. Outside, the annular relay member 7 and the fixing member 8 are concentrically arranged. The objective lens holder 9 and the relay member 7 are connected and supported by a pair of support members 5a and 5b. Also,
The relay member 7 and the fixing member 8 are paired with a pair of support members 6a, 6
b.

The pair of support members 5a and 5b and the pair of support members 6a and 6b are adapted to rotatably support the objective lens 2 in two inclination directions orthogonal to the optical axis 4 of the objective lens 2. Are arranged orthogonally to each other. That is, the rotation axes of the pair of support members 5a and 5b and the pair of support members 6a and 6b are oriented in two directions orthogonal to the optical axis 4 of the objective lens 2, and are orthogonal to each other.

Each of the pair of support members 5a and 5b and the pair of support members 6a and 6b is made of a wire-like elastic body having a circular cross section and arranged symmetrically with respect to the optical axis with the objective lens interposed therebetween. . Among these support members, the rotation center axes of a pair of support members 6a and 6b disposed far from the optical axis coincide with the disk radial direction (disc radial direction), and are respectively supported by the support members. And the center of gravity of the rotating part, and is disposed on the same plane perpendicular to the optical axis.

Further, since the same plane perpendicular to the optical axis coincides with the main plane of the objective lens, the beam spot on the disk does not move with the rotation of the objective lens 2. The objective lens 2 is centered on the support members 5a and 5b by an electromagnetic force generated between the magnets 10a and 10b attached to the objective lens holder 9 and the rectangular cylindrical coils 12a and 12b attached to the relay member 7. Then, it turns in the disk radial direction. Also, the objective lens 2
Magnets 11a and 11b attached to the relay member 7
And the rectangular tubular coil 13 attached to the fixing member 8
a, 13b, the support member 6
Rotate in the disk tangential direction around a and 6b.

The present embodiment has a so-called moving magnet configuration in which a magnet is attached to the rotating part and a coil is attached to the fixed part side. Conversely, a coil is attached to the rotating part. Alternatively, a so-called moving coil configuration in which a magnet is attached to the fixed portion side may be used. Needless to say, the magnetizing direction and the coil energizing direction of each magnet in the moving magnet configuration and the moving coil configuration may be arbitrarily set so that the objective lens 2 can rotate in a predetermined direction.

Next, the above-described objective lens tilt driving device 1
FIG. 4 shows an embodiment in which the optical disc drive is configured to be biaxially movable in the focusing direction and the tracking direction in addition to the disc radial rotation direction and the disc tangential rotation direction.

FIG. 4 is a plan view. The holder 14 on which the objective lens tilt driving device 1 is disposed has four wires 1
5 support the lens so that it can be displaced in the focusing direction and the tracking direction. One end of the wire 15 is attached to the holder 14 and the other end is attached to the fixed base 16. Focusing coils 17a and 17b having a rectangular cylindrical shape are attached to the holder 14.

On the surface of the focusing coil 17a,
Flat tracking coils 18a and 18b are provided, and flat tracking coils 18c and 18d are provided on the surface of the focusing coil 17b, respectively. Further, a pair of magnetic circuits 21a each composed of a magnet 19a and yokes 20a and 20b, and a pair of magnetic circuits 2 each composed of a magnet 19b and yokes 20c and 20d.
1b are arranged to face each other with the holder 14 interposed therebetween.

Further, a part of the focusing coil 17a and the tracking coils 18a and 18b is
A part of the focusing coil 17b and a part of the tracking coils 18c and 18d are arranged in the magnetic gap 22b of the magnetic circuit 21b. Therefore, focusing coil 1
7a, 17b and tracking coils 18a, 18b,
The holder 14 is driven and controlled in a focusing direction and a tracking direction by a predetermined electromagnetic force (Lorentz force) generated in 18c and 18d.

With the above-described configuration, the objective lens 2 can be tilted and driven at high speed in two directions of the disk radial rotation direction (disc radial direction) and the disk tangential rotation direction (disc circumferential direction). Further, an objective lens four-axis actuator capable of driving the objective lens 2 at high speed in the focusing direction and the tracking direction can be realized. As described above, an extremely compact, low-power, high-performance objective lens four-axis actuator can be realized.

Next, an embodiment in which the objective lens tilt driving device 1 according to the first embodiment of the present invention is disposed on the bobbin 24 of the optical system-integrated two-axis actuator 23 will be described with reference to FIG. Will be explained. FIG. 5 is a schematic sectional view thereof.

In FIG. 5, the bobbin support member, focusing coil, tracking coil, and magnetic circuit, which are components of the optical system-integrated two-axis actuator 23, are not shown. These bobbin support members, focusing coils, tracking coils, and magnetic circuits can be arranged at appropriate positions. The bobbin 24 is provided with the objective lens tilt driving device 1, a reflection mirror 25, and a mount block 26. Mount block 26
, A semiconductor laser chip, a photodetector, and the like (not shown) are mounted. As described above, only by disposing the objective lens tilt driving device 1 on the optical system-integrated two-axis actuator 23, it is possible to realize an optical system-integrated four-axis actuator that can respond to the inclination of the optical disk at high speed.

In the objective lens tilt drive device according to the second embodiment of the present invention, the objective lens tilt drive device according to the above-described first embodiment of the present invention has two pairs of support members,
An elastic body made of a resin material and having a hinge shape. FIG. 6 is a plan view showing a configuration of an objective lens tilt driving device according to a second embodiment of the present invention, FIG. 7 is a cross-sectional view taken along line AA of FIG. 6, and FIG. It is sectional drawing seen from the B line.

In this embodiment, the support members 5a, 5a
b, 6a, and 6b have hinge portions 27. The hinge portion 27 has a shape in which a thin portion at each end of a cone and an inverted cone is connected. Support members 5a, 5b made of a resin material;
By providing the hinge portions 27 on 6a and 6b, a large damping effect at the time of rotation can be realized. The optical axis 4 of the objective lens 2 during tracking and seek
The lens shift in the direction perpendicular to the direction can be extremely reduced.

The relay member 7, the fixing member 8, the objective lens holder 9, and the supporting members 5a, 5b, 6a, 6b are
By integrally molding by injection, a high-precision objective lens tilt drive device with extremely excellent mass productivity can be realized. In addition, the shape of the hinge portion 27 is not limited to the above-described shape, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

[0034]

As described above, in the objective lens tilt driving device according to the present invention, the respective rotation center axes of the two pairs of support members for supporting the objective lens are disposed on the same plane orthogonal to the optical axis. And the same plane perpendicular to the optical axis coincides with the main plane of the objective lens. Therefore, the driving means provided to rotate the objective lens in the tilt direction of the optical axis causes the objective lens to rotate. Even if the lens is rotated in one direction perpendicular to the optical axis of the objective lens, the beam spot on the disk is shifted in the disk radial direction (disc) because the center of rotation of the objective lens is always at the principal point of the objective lens. The actuator does not move in the radial direction) and the disk tangential direction (the tangential direction of the disk), and stable actuator control can be realized.

Further, since the extremely small and lightweight rotating portion, which is composed of the objective lens and a part of the driving means, is rotated at a predetermined angular acceleration in the direction of inclination of the optical axis of the objective lens, the driving force is small. As a result, power consumption can be reduced.
In this way, the inclination of the beam optical axis with respect to the disk recording surface can be corrected with low power consumption, high performance, and high speed in response to the change in the amount of warpage during one round of the disk.

Further, the objective lens tilt driving device is configured to be biaxially movable in the focusing direction and the tracking direction in addition to the disk radial rotation direction and the disk tangential rotation direction, so that it is extremely compact.
A high-performance objective lens four-axis actuator with low power consumption can be realized. Further, by providing the objective lens tilt drive device on the bobbin of the optical system-integrated two-axis actuator, it is possible to realize an optical system-integrated four-axis actuator that can respond to the tilt of the optical disk at high speed.

Further, by providing the support member with the hinge portion, a large damping effect can be realized at the time of rotation, and a lens shift in a direction perpendicular to the optical axis 4 of the objective lens 2 at the time of tracking and seeking. Can be made extremely small. Further, by integrally molding the relay member, the fixing member, the objective lens holder, and the support member by injection, it is possible to realize a highly accurate objective lens tilt driving device which is extremely excellent in mass productivity.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of an objective lens tilt drive device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 shows a configuration in which the objective lens tilt driving device according to the first embodiment of the present invention is movable in two axes in a focusing direction and a tracking direction in addition to a disc radial rotation direction and a disc tangential rotation direction. FIG.

FIG. 5 is a schematic cross-sectional view showing a configuration in which the objective lens tilt drive device according to the first embodiment of the present invention is disposed on a bobbin of an optical system-integrated two-axis actuator.

FIG. 6 is a plan view showing a configuration of an objective lens tilt drive device according to a second example of the present invention.

FIG. 7 is a sectional view taken along line AA in FIG. 6;

FIG. 8 is a sectional view taken along line BB of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Objective lens tilt drive device 2 ... Objective lens 3 ... Incident light beam 4 ... Optical axis 5a, 5b, 6a, 6b ... Support member 7 ... Relay member 8 ... Fixing member 9 ... Objective lens holder 10a, 10b, 11a, 11b ... Magnets 12a, 12b, 13a, 13b Rectangular cylindrical coil 14 Holder 15 Wire 16 Fixed base 17a, 17b Focusing coil 18a, 18b, 18c, 18d Tracking coil 19a, 19b Magnet 20a, 20b, 20c Reference numerals 20d: yokes 21a, 21b: magnetic circuits 22a, 22b: magnetic gaps 23: optical system integrated two-axis actuators 24: bobbins 25: reflection mirrors 26: mount blocks 27: hinge portions

Claims (6)

[Claims] An objective lens for condensing light on an optical disk; a pair of first support members rotatably supporting the objective lens in a first tilt direction of an optical axis thereof; A relay member fixed to a part of the support member, and a part thereof is attached to the relay member, and supports the objective lens rotatably in a second tilt direction orthogonal to the first tilt direction. A pair of second support members, a fixed member to which a part of the pair of second support members is fixed, and the objective lens are moved in a first tilt direction with the first support member as a rotation axis. And a driving means for rotating in a second tilt direction about the second support member as a rotation axis, wherein each of the first and second support members is Disposed symmetrically with respect to the optical axis with respect to the objective lens. Objective lens tilt driving apparatus characterized by comprising a pair of elastic bodies have. 2. The objective lens tilt driving device according to claim 1, wherein the first and second tilt directions correspond to a disc radial direction and a disc tangential direction, respectively. 3. The objective lens tilt driving device according to claim 2, wherein a rotation center axis of the second support member coincides with the disk radial direction. 4. The rotation center axis of each of the first and second support members includes a center of gravity of a rotation part that the first and second support members respectively support and rotate. Item 4. The objective lens tilt drive device according to any one of Items 1 to 3. 5. The objective lens according to claim 4, wherein respective rotation center axes of the first and second support members are disposed on the same plane orthogonal to the optical axis. Tilt drive. 6. The objective lens tilt driving device according to claim 5, wherein the same plane orthogonal to the optical axis is a main plane of the objective lens.